The present invention relates to a catalyst for reforming a hydrocarbon, a production process for the same and a process for reforming a hydrocarbon using the above catalyst, more specifically to a catalyst for reforming a hydrocarbon in which manganese oxide is used for a part of a carrier, a production process for the same and a process for steam reforming, self thermal reforming, partial oxidation reforming and carbon dioxide reforming for a hydrocarbon using the above catalyst.
In recent years, new energy technologies are spotlighted from the viewpoint of environmental problems, and a fuel cell attracts attentions as one of the new energy technologies. In this fuel cell, hydrogen is electrochemically reacted with oxygen to thereby convert chemical energy to electric energy, and it is characterized by having a high use efficiency of energy, so that researches for putting it to practical use are positively carried out for civil, industrial and automobile applications. In this fuel cell, types such as a phosphoric acid type, a molten carbonate type, a solid oxide type and a solid polymer type are known according to the kind of electrolytes used. On the other hand, used as a hydrogen source are methanol, a liquefied natural gas comprising mainly methane, a city gas comprising this natural gas as a principal component, a synthetic liquid fuel comprising a natural gas as a raw material and petroleum base hydrocarbons such as naphtha and kerosene.
When using these hydrocarbons to produce hydrogen, the above hydrocarbons are usually subjected to steam reforming treatment in the presence of a catalyst. In this case, a catalyst carried thereon with ruthenium as an active ingredient has so far been researched as a catalyst for steam reforming treatment of petroleum base hydrocarbons. It has the advantages that it has a relatively high activity and that carbon is inhibited from being deposited even under an operating condition of a low steam/carbon ratio, and in recent years, it is expected to be applied to a fuel cell requiring a catalyst having a long life.
On the other hand, since it has been found that cerium oxide and zirconium oxide have a promoter effect for a ruthenium catalyst, catalysts which are based on cerium oxide, zirconium oxide and ruthenium are researched, and several patents have been applied. For example, the case of cerium oxide includes Japanese Patent Publication No. 29633/1984, Japanese Patent Application Laid-Open No. 147242/1985, Japanese Patent Application Laid-Open No. 281845/1992, Japanese Patent Application Laid-Open No. 10586/1997, Japanese Patent Application Laid-Open No. 173842/1997, Japanese Patent Application Laid-Open No. 262486/1997, Japanese Patent Application Laid-Open No. 24235/1998and Japanese Patent Application Laid-Open No. 61307/2000. Further, the case of zirconium oxide includes Japanese Patent Application Laid-Open No. 168924/1993, Japanese Patent Application Laid-Open No. 208133/1993, Japanese Patent Application Laid-Open No. 220397/1993, Japanese Patent Application Laid-Open No. 261286/1993, Japanese Patent Application Laid-Open No. 88376/1995, Japanese Patent Application Laid-Open No. 48502/1996, Japanese Patent Application Laid-Open No. 196907/1996, Japanese Patent Application Laid-Open No. 29097/1997 and Japanese Patent Application Laid-Open No. 29098/1997. Further, catalysts based on platinum, rhodium, palladium, iridium and nickel in addition to ruthenium have been researched as well. However, they do not necessarily have a satisfactory activity as a steam reforming catalyst for hydrocarbons, and the problem that a large amount of carbon is deposited still remains.
In producing hydrogen, self thermal reforming treatment, partial oxidation reforming treatment and carbon dioxide reforming treatment in addition to steam reforming treatment have been researched as well, and it is known that in general, all the reforming treatments described above can be carried out with the same reforming catalyst. Further, it is known as well that a synthetic gas can be produced by all the reforming treatments described above by changing a little the conditions. Ruthenium, platinum, rhodium, palladium, iridium and nickel as a catalyst have been researched for the self thermal reforming treatment, the partial oxidation reforming treatment and the carbon dioxide reforming treatment each described above, but they are still unsatisfactory in terms of an activity.